Narrative:American Airlines Boeing 767 N330AA flew as flight AA201 from New York-JFK (JFK) to Los Angeles (LAX). During a step climb from FL360 to FL380 en route to LAX, the pilots noted that the No. 1 engine was lagging the right engine by about 2 percent. The flight landed at LAX at 09:37. After the passengers had disembarked, the plane was towed to hangar no. 2 and was parked outside. Maintenance personnel were going to conducting a ground run to troubleshoot the reported discrepancy. Several engine runups to maximum power were performed on both engines. Then they did two runups to max power of just the no. 1 engine. When retarding the throttle to idle, the engine experienced an uncontained rupture of the high pressure turbine (HPT) stage 1 disk. Debris punctured the fuselage and fell onto adjacent runway and taxiways. Runway 25R and Taxiways B and C were closed for several hours until the investigation and collection of the debris could be accomplished. The engine caught fire and the plane sustained significant damage to the left wing, fuselage, and tail section.

PROBABLE CAUSE: "The HPT stage 1 disk failed from an intergranular fatigue crack because of GE's inadequate design of the CF6-80 series HPT stage 1 disk. The inadequate design of the disk resulted in a high stress area in the blade slot bottom aft corner that was at or nearly at the material's capability so that there was no damage tolerance such that a small dent could cause a crack to initiate and propagate to failure. Contributing to the disk's failure was the FAA's failure to mandate an accelerated inspection schedule after a previous CF6-80A uncontained HPT stage 1 disk failure had occurred and after other CF6-80A HPT disks had been found during routine overhaul to have cracks in the blade slot bottom aft corners."

Included a schedule for maintenance -- removal, inspection, and reworking -- of CF6-80 series HPT stage 1 disks beginning at 6,900 cycles.

Issued: 28-AUG-2006

To: FAA

A-06-060

Require that all CF6-80A and -80C2 high pressure turbine (HPT) stage 1 disks and applicable -80E1 HPT stage 1 disks that have more than 3,000 cycles since new (CSN) and have not been reworked in accordance with General Electric Service Bulletins (SB) 72-0788 or 72-1089 or have not yet been inspected in accordance with SB 72-0779 or Alert Service Bulletin 72-A1026 be immediately removed from service for inspection and rework in accordance with these SBs. Those CF6-80A and -80C2 HPT stage 1 disks and applicable -80E1 HPT stage 1 disks that have fewer than 3,000 CSN and have not been reworked or inspected in accordance with these SBs can remain in service until reaching the 3,000 CSN threshold, at which time they should also be removed from service for inspection and rework. (Urgent) (Closed - Unacceptable Action)

Issued: 28-AUG-2006

To: FAA

A-06-061

Require that all CF6-80A and -80C2 high pressure turbine (HPT) stage 1 disks and applicable -80E1 HPT stage 1 disks that have not been reworked in accordance with General Electric Service Bulletins (SB) 72-0788 or 72-1089 but have been inspected in accordance with SB 72-0779 or Alert Service Bulletin (ASB) 72-A1026 and have more than 3,000 cycles since the inspection be immediately removed from service for reinspection and rework in accordance with these SBs. Those CF6-80A and -80C2 HPT stage 1 disks and applicable -80E1 HPT stage 1 disks that have not been reworked in accordance with SBs 72-0788 or 72-1089 but have been inspected in accordance with SB 72-0779 or ASB 72-A1026 and have fewer than 3,000 cycles since the inspection can remain in service until reaching the 3,000 cycles-since-inspection threshold, at which time they should also be removed from service for reinspection and rework. (Urgent) (Closed - Unacceptable Action)

Require a design review of CF6-80 series high pressure turbine (HPT) stage 1 disks that incorporate chamfered blade slot bottom aft corners that includes a stress analysis and finite element model emphasizing the blade slot bottom aft corner to determine whether sufficient material property margin exists to ensure that cracks do not occur. If the design review of chamfered HPT stage 1 disks finds that this design does not provide sufficient material property margin, then a redesign or material change should be implemented. (Closed - Acceptable Action)

Issued: 28-AUG-2006

To: FAA

A-06-064

Require that maintenance personnel ensure that an aircrafts cockpit voice recorder (CVR) is operating before conducting any engine ground tests. If an airplane has been involved in a reportable event, the incident CVR should be removed to preserve the event data and any subsequent ground test should be delayed until a suitable replacement CVR can be installed in the aircraft. (Closed - Unacceptable Action)